Detailed Description

Represents additional information associated with a scalar in schema.
`categorical_limit` - for fields of integral type that are guaranteed to be
non-negative it specifies the maximum possible value plus one. It's often
used as a size of an embedding table.
`expected_value` - anticipated average value of elements in the field.
Usually makes sense for length fields of lists.
`feature_specs` - information about the features that contained in this
field. For example if field have more than 1 feature it can have list of
feature names contained in this field.